When I first came to this forum I didn't really have a word for what I was. Through reading what is here I soon realised that I was a 'dominant', and then as time progressed I also realised I had more than a little sadism in me. In fact, parts of what I do with lucy could only (I think) be described as hardcore sadism (burning her with a cigar or naked flame, whipping her with a chain, etc).
The sadism doesnt have to be just (thinks of the right word) .. dramatic(?) pain in that way. For instance, I just cannot resist playing with her nipples when they are already tender and swollen from whatever was done to them in a scene. So, after a scene when we are dressed, chatting or just watching tv, my hands continually move to her nipples to continue to give her pain for no reason other than my wish to see her wince and whimper. This won't lead to another scene (ok, I lie ... sometimes it does) but is more just an expression of how much I cannot resist touching her and giving her pain.
However, I have also realised that unless she 'wants' pain then it does nothing for me, to the extent that I just have no wish to continue. I am not sure if that is true sadism - only wishing to give pain when the recipient is grateful to receive it somehow seems to not quite fit with the definition of 'sadism' that I have in my head.